1. Field of the Invention
The present invention relates to oxy/fuel fired distribution channels and their use in glass making and to oxy/fuel combustion methods and burners which may be used in a distribution channel.
2. History of the Prior Art
In the production of glass, a distribution channel has two main purposes. First, the distribution channel delivers molten glass from the furnace to the forming means. Second, the distribution channel modifies the temperature of the molten glass. Usually, the temperature of the molten glass must be lowered.
Modifying the temperature of the molten glass brings the glass to a viscosity required for forming. Viscosity requirements vary widely depending on the glass and forming means used. Uniformity of temperature for all glass entering the forming means is the measure of excellence. Uniformity of gob weight or product dimensions are dependent upon uniform temperatures in the gob.
However, modifying the temperature of molten glass in a distribution channel is difficult due to temperature differences existing in the glass. The glass at the sides of the distribution channel is cooler than the glass in the center of the distribution channel. This is because the glass at the sides of the channel transfers heat through the walls of the channel, while the glass in the center of the channel is insulated from heat loss by the surrounding glass.
Thus, it is usually necessary to heat the glass at the sides of the distribution channel so as to raise its temperature to that of the glass in the center of the channel. Conversely, the glass in the center of the distribution channel is usually simultaneously cooled so as to lower its temperature to that of the glass at the sides of the channel.
The temperature of the glass at the sides of the distribution channel is commonly raised with burners. Recently, a few glassmakers have tried oxy/fuel burners in place of air/fuel burners. Compared with air/fuel burners, oxy/fuel burners provide three times the available heat from the same fuel input and a significant reduction in NOx.
One major problem has historically plagued the practice of heating the glass at the sides of a distribution channel with burners. The heat produced by the burners travels to the center of the channel. This heats the glass in the center of the channel, which should be cooled.
To deal with this problem, wind cooling of the center of the distribution channel and "wings" substantially separating the center and sides of the channel have been utilized. However, energy from the burners still makes its way to the center of the channel, where the heating flames and cooling wind compete, making temperature uniformity difficult to achieve. Therefore, a need exists for a method of making glass comprising an improved method of modifying the temperature of the molten glass in a distribution channel.